4 ms·

The field's (quantum physics') moving back and freely between: Serious Math; ill-advised specialist terminology that borrows then twists common words in just th

by asark 8y ago

The field's (quantum physics') moving back and freely between: Serious Math; ill-advised specialist terminology that borrows then twists common words in just the worst ways; and seemingly metaphysical stories or explanations that are... literal? Metaphorical? Full of borrowed BS words from point two that fall out of the math but don't "mean" anything in everyday terms? Definitely one of those until you ask a question then you're an idiot and it's another, until it's not again? Has put me off any childlike interest I once had in it. It seems fun. But I can't tell when they're serious or screwing with me. Sometimes one person claims something's serious, and they do so with authority, and another says they're screwing with me with just as much authority. I gave up. Somewhat relatedly[0], I can't find an explanation of the Oberth Effect that makes any damn sense. Every so often I try again and leave disappointed. People are happy to provide them. There are lots of them. They attribute it to all sorts of things. Not one of them I've read makes sense. [0] i.e. is physics, but is not quantum physics. So far as I know, anyway.

Baeocystin 8y ago
>I can't find an explanation of the Oberth Effect that makes any damn sense. It's simpler than people make it. When a spacecraft is moving at a high velocity, the amount of kinetic energy embodied by its fuel mass is a significant fraction of the chemical energy already present. And kinetic + chemical is greater than chemical alone. That's all there is to it.
a1369209993 8y ago
> I can't find an explanation of the Oberth Effect that makes any damn sense I'll take a crack at it: Kinetic energy plus gravitational energy is conserved when you aren't actively accelerating[0]. Rocket fuel has kinetic and/or gravitational energy in addition to it's chemical energy. If you burn the fuel while going very fast[1], you can extract it's kinetic energy by bringing the exhaust to(wards) a stop. When going slowly[2], you end up spending energy to accelerate the exhaust away from you, and you also can't really do anything to get at its gravitational energy[3]. 0: Ie, thrusting your engines or crashing; things that involve g-forces; not freefall. 1: That is, when most of its gravitational+kinetic energy is in kinetic form. 2: With energy mostly in gravitational form. 3: Gravitational energy is a function of where mass is at that exact moment; if you're high away from a gravity well, you have lots of energy tied up as gravitational, and no quick way to turn it into a more useful form.
improbable22 8y ago
To be fair, "quantum physics" is much too broad a brush here, your issue is with "quantum interpretations" or something -- I'm not sure this subfield has a really firm label. But it's fully of people tripping over paradoxes they invented and encouraging you to likewise stumble and admire how cleverly they tried to disguise their handiwork. In content it's unclear we've learned anything new here in the last 50 years. But straight "quantum physics" covers lots of other, more solid, areas. Including understanding how lots of things you can actually manufacture work, like semiconductors and superconductors.
- tupshin 8y ago
  https://en.m.wikipedia.org/wiki/Quantum_foundations https://en.m.wikipedia.org/wiki/Quantum_foundations

by asark 8y ago

Baeocystin 8y ago

>I can't find an explanation of the Oberth Effect that makes any damn sense. It's simpler than people make it. When a spacecraft is moving at a high velocity, the amount of kinetic energy embodied by its fuel mass is a significant fraction of the chemical energy already present. And kinetic + chemical is greater than chemical alone. That's all there is to it.

a1369209993 8y ago

> I can't find an explanation of the Oberth Effect that makes any damn sense I'll take a crack at it: Kinetic energy plus gravitational energy is conserved when you aren't actively accelerating[0]. Rocket fuel has kinetic and/or gravitational energy in addition to it's chemical energy. If you burn the fuel while going very fast[1], you can extract it's kinetic energy by bringing the exhaust to(wards) a stop. When going slowly[2], you end up spending energy to accelerate the exhaust away from you, and you also can't really do anything to get at its gravitational energy[3]. 0: Ie, thrusting your engines or crashing; things that involve g-forces; not freefall. 1: That is, when most of its gravitational+kinetic energy is in kinetic form. 2: With energy mostly in gravitational form. 3: Gravitational energy is a function of where mass is at that exact moment; if you're high away from a gravity well, you have lots of energy tied up as gravitational, and no quick way to turn it into a more useful form.

improbable22 8y ago

To be fair, "quantum physics" is much too broad a brush here, your issue is with "quantum interpretations" or something -- I'm not sure this subfield has a really firm label. But it's fully of people tripping over paradoxes they invented and encouraging you to likewise stumble and admire how cleverly they tried to disguise their handiwork. In content it's unclear we've learned anything new here in the last 50 years. But straight "quantum physics" covers lots of other, more solid, areas. Including understanding how lots of things you can actually manufacture work, like semiconductors and superconductors.

tupshin 8y ago
https://en.m.wikipedia.org/wiki/Quantum_foundations https://en.m.wikipedia.org/wiki/Quantum_foundations